The question of truth is vital to this reading of Mansfield Park in three important ways. First, there is the pursuit of truth represented by the conversations--both internal and external-- of characters int he novel. There is the truth--or realism--of that representation itself, as manifest by specific narrative techniques (especially with dialogue) of which Austen is an innovator. Finally, there is the larger truth--as effected by a combination of the first two--that conveys itself to the reader. Constancy plays a role in all three expressions of truth. It grounds the right pursuit of truth--enacted by Fanny--whose "hermeneutical" habit and growing clarity of vision contrasts with the inflexible blindness to truth in those around her. In some instances, constancy--in particular its development--also is enacted by Austen's use of narrative techniques; the reverse--the lack of its development--may also be suggested thereby. Finally, from the process of reading and responding to the novel's truth, readers may approximate a kind of constancy that allows them to grow in self-knowledge--discovering truths about themselves that may lead to transformation.
Joyce Kerr Tarpley, Constancy and the Ethics of Jane Austen's Mansfield Park, p. 182.